Infections are common following surgery and it is critically important to identify infection quickly to avoid readmission and more serious infection and even sepsis. Early detection allows time for simple antibiotics to be effective avoiding surgical readmissions. The Centers for Medicare & Medicaid Services recognize the serious nature of the problem and will start imposing significant penalties for surgical readmissions in 2015. In addition, early treatment enhances the probability that surgical implants and prosthetics remain viable because they almost always have to be replaced if infection takes hold. Inflammation is the earliest physiologic marker of infection but it has many sources so it must be localized to the wound using local measurements made over time. Further the inflammation caused by normal wound healing can be isolated from that produced by infection by monitoring it over time. Inflammation from wound healing begins within hours and abates completely a few days after surgery with the initiation of the proliferative phase. Inflammation from infection increases monotonically and reach far higher levels. So we believe that infection can be identified early by measuring continued local inflammation. We will use the cytokine concentration (IL-6 will be used first) and the local temperature as markers for inflammation. We will use our measures of the magnetic nanoparticle temperature and the local concentration of IL-6 to identify infection.